The present invention generally relates to a method of controlling the valve within a fuel injector. More specifically, the present invention relates to a method of controlling the electrical current through a solenoid which opens and closes the valve of the fuel injector.
Within an internal combustion engine fuel injector, a valve selectively opens and closes to either allow fuel to flow through the fuel injector or to stop fuel from flowing through the fuel injector. Typically, the valve within a fuel injector is controlled by a spring and a solenoid, wherein the valve overcomes the force of the spring and opens when an electrical current is supplied to the solenoid, and the spring forces the valve to close when the electrical current is removed. When an electrical voltage is first supplied across the solenoid, there is a lag time before the opening of the valve. During this lag time the magnetic circuit energizes and the current through the solenoid, which is predominantly an inductor, increases until reaching a sufficient level to start moving the valve. Similarly, when the electrical current through the solenoid is removed, the energy stored in the inductor of the solenoid must be dissipated before the spring begins to close the valve. Fuel flowing through the fuel injector will not stop until the current through the solenoid dissipates enough to allow the valve to close.
This lag time causes hesitation before fuel is supplied through the fuel injector, and causes additional fuel to flow into the cylinder of the engine before the valve fully closes. Long and unpredictable lag times cause errors in fuel timing and volume, negatively affecting fuel economy, emissions, and performance. Therefore, there is a need for an improved method of controlling the opening and closing of the valve within an internal combustion engine fuel injector that will minimize the lag time between opening and closing of the valve.